Hilltop Holstein Dairy and Vanderschaaf Dairy High-Solids 700 Dekatherm Anaerobic Digester Projects

Our Plumbing/Piping and HVAC team had the unique opportunity to partner with Opal Fuels to build one of the first anaerobic digester projects in the Sacramento Central Valley. These two projects are identical closed-loop energy system facilities designed to capture the natural gas contained in cow manure, which can then be converted to renewable natural gas, electricity, heat, and fertilizer, to reduce greenhouse gases.

The Vanderschaaf Dairy is unique in design as it includes pumping semi-solid manure from a sludge pond located on an adjacent dairy (Donor site) for processing (separating solids from water). The processed water is then returned back to the adjacent dairy, to then be used to flush the feed barns' floors.

A Unique Scope of Work

Our scope of work for these two projects was the fabrication and installation of Sch40 304L stainless steel (ranging in sizes from 2” through 24”), as well as four sets of “heat-ring loops” designed using 4” Sch10 304L Stainless Steel pipe, which were bent in sections by Stockton Tri Industries based in Stockton, CA. These were mounted on fabricated stainless-steel wall supports installed inside the “hydrolyzer” concrete tank used to ensure the semi-solid manure mixture was kept a consistent temperature.

The “heat-ring loops" were served by a central plant which housed (3) Fulton EDR-1500 BTU Boilers, (6) 260gpm Inline Taco pumps, (1) 330gpm Inline Taco pump, and (1) 1220gpm Inline Taco pump, and associated piping and valves.

The project also included excavation and installation for 3000lf of SDR17 HDPE IPS 3408PE pipe and fittings ranging in sizes from 2” to 24” below-grade piping.